Estimated Number of Mumps Cases Based on Clinical and Laboratory Data from Sentinel Surveillance in Kanazawa, Japan

Area of Science:

• Epidemiology
• Infectious Diseases
• Vaccinology

Background:

• Mumps vaccination is not routine in Japan, hindering accurate disease burden estimation.
• Current sentinel surveillance relies on clinical diagnosis (parotid swelling), which lacks specificity.
• This leads to inaccurate mumps case counts and underestimation of associated complications.

Purpose of the Study:

• To accurately estimate the disease burden of mumps in Japan.
• To assess the utility of laboratory-based surveillance for mumps.
• To inform policy decisions regarding routine mumps vaccination.

Main Methods:

• Conducted laboratory-based surveillance at a single sentinel site in Kanazawa.
• Collected data during a mumps endemic period (2015-2016).
• Estimated mumps cases using laboratory-confirmed results and compared with clinically compatible cases.

Main Results:

• Estimated 3,881 laboratory-confirmed mumps cases (95% CI: 3,404-4,357).
• Laboratory-confirmed cases were approximately 1,000 fewer than clinically compatible cases.
• Potential for hearing loss due to mumps may be 40% higher than currently reported.

Conclusions:

• Laboratory-based surveillance provides a more accurate estimate of mumps disease burden.
• Despite fewer confirmed cases, mumps poses a significant risk for complications like hearing loss.
• Implementing surveillance with diagnostic testing is vital for advocating routine mumps vaccination.